1. Field of the Invention
Immunological therapy, in particular regeneration of T.sub.4 lymphocytes and reduction of opportunistic infections in AIDS patients.
2. Discussion of the Prior Art
9-Amino-1,2,3,4-tetrahydroacridine, generally known by its tradename of Tacrine, has been reported to be useful in the treatment of memory disorders such as Alzheimer's Disease. European Patent application, Publication Nos. 0306825 and 0306826 of 1989, disclose certain N-substituted alkylidine derivatives of Tacrine which are, optionally, also substituted in the acridine ring. Compounds in this category are also mentioned by R. Faure, J. Chim. Phys. Chim. Biol., 78(6) (1981) 527; Khim, Pharm. Zhur., 5(11), (1971) 10-12; Baveja, Ind. J. Pharm. Sci., 48 (1986), 23-25. It has been reported by J. Byrne and T. Acie, British Med. J. 298, (1989) (845) that long term administration of Tacrine is not practical because of hepatotoxicity. More recent studies by Applicants have shown that this problem of hepatotoxicity can be avoided by utilizing purified sources of Tacrine.
T.sub.4 lymphocytes are well known to be important cells in the human immunodefense mechanism. Heretofore, reliable methods of increasing T.sub.4 levels which have been depressed by disease, have not been available. Stimulating the regeneration of T.sub.4 cells therefore, would be a highly desirable achievement. The reduction of opportunistic infections in AIDS patients is a desirable result of stimulating immune responses in such patients. In many cases a reduction P.sub.24 antigenaemia levels is an indication of such improved responses.